That force size is expected to grow to 2,500 total US troops in the months to come.

The move has been widely interpreted as a signal to China, with its rising military force helmed by commanders who are often less-than-transparent in their intentions, Pentagon officials often complain.

Yet military officials stress that the focus of the US troops will first and foremost be on goals that don’t involve China. “There are two big thrusts here. One is obviously training with Australian defense forces and strengthening our already strong alliance with them,” says Capt. Greg Wolf, a US Marine Corps spokesman.

The other is to deploy throughout the region to participate in theater exercises “and further regional security in that part of the world,” Captain Wolf adds.

The Marines will also be on hand to respond to humanitarian disasters, such as the tsunami that swept through southeast Asia and last year’s earthquake in Japan.

Australian officials have been slightly more provocative regarding the US troop arrival. “The world needs to essentially come to grips with the rise of China, the rise of India, the move of strategic and political and economic influence to our part of the world,” Australian Defense Minister Stephen Smith said as he greeted the charter flight carrying the company of US Marines.

“We see this very much as responding and reflecting the fact that the world is moving into our part of the world, the world is moving to the Asia Pacific and the Indian Ocean. We need to respond to that,” he added.

The American ambassador to Australia, however, pushed back against the notion that the Pentagon’s troop influx into the region is primarily aimed at containing China. “There’s this kind of sexy, fun narrative that you hear from pundits and others trying to suggest this is about China,” said US ambassador Jeffrey Bleich, “but it’s not.”

Pentagon officials have made no secret about their concerns involving China, though. Adm. Samuel Locklear III, who heads US Pacific Command, for his part describes the US military’s relationship with China as “cooperative, but competitive.”

“We’re an Asian power,” Admiral Locklear said of the United States in testimony before the Senate Armed Services Committee in February. “We have interest in that part of the world. And I believe that the Chinese and other people in that part of the world need to recognize that we do have US national security interests there.”

Locklear, along with other US military officials, has called for expanded cooperation between the American and Chinese militaries, which could help reduce any tensions that could potentially lead to conflict. “Greater transparency is good for all of us to avoid miscalculation,” he said.

As the new Pacific Command head, Locklear told lawmakers that his “plan” will be to “improve our ‘mil-to-mil’ relationships – with a recognition that there are things we won’t agree on.”